JPH02146959A - Single ended conduction type converter with transformer and demagnetizer - Google Patents

Abstract

PURPOSE: To eliminate the waste of demagnetizing energy by choosing a capacitance such that a resonance circuit formed of the capacitance of the capacitor of a demagnetizing device and the shunt inductance of a transformer has a resonance frequency approximately equal to a main resonance circuit. CONSTITUTION: A demagnetizing device for demagnetizing the core of a transformer after the turn-on phase of an electronic switch S includes an additional capacitor C3, connected to the secondary winding W2 of the transformer. The capacitance of the additional capacitor C3 is chosen, so that an additional resonance circuit of the capacitor C3 and the shunt inductance Lq of the transformer has a resonance frequency which is equal to the main resonance frequency of a resonance circuit, including an inductance L1 and a capacitance C1. In fact, no inductive voltage peak is generated in the electronic switch S, at the time of its being cut off by using a demagnetizing network.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a single-ended ψ through-type f-arm which includes a transformer and has a demagnetizing device.

The prior art single-ended conduction type converter is disclosed in U.S. Patent No. 4.41.
5.956 ψ1 Thin tVC. The transformer in this patent is intentionally provided to include a leakage inductance that forms a resonant circuit with the storage capacitor. The electronic switch opens at the end of the half cycle of the sinusoidal current, then the Fi no current condition. In the control of electronic switches with control circuits, the off time during which the switch is open circuit is different from the constant on time.

A part of the LC filter is connected after the freewheeling diode, and a 71 nowheeling diode is connected in parallel after the storage capacitor. Such a freewheeling diode becomes energized during each energy transfer cycle as soon as the storage capacitor has been substantially discharged.

Demagnetization of the transformer after the end of the on-time is carried out by using electronic switches or by using a suitable circuit network. U.S. Pat. No. 4.441.14
No. 6 discloses a demagnetizing device for conductive converters, which has a series circuit of a capacitor and an electronic switch in the control circuit. The demagnetizing device of Jin's invention is relatively expensive.

OBJECTS OF THE INVENTION It is an object of the invention to provide a single-ended conductive transducer in which a relatively inexpensive demagnetizing device is provided and ideally no demagnetizing energy is wasted. be.

According to the present invention, a single-ended conduction type converter is formed including a transformer, and the first primary winding in the primary circuit of the transformer is connected to a DC source QKM through an electronic switch S. , an electronic switch is alternately turned on and off by a control pulse, and two of the transformers
Secondary winding # in the next circuit! W2 is connected to the storage capacitor 01 over the kiA circuit, which together with the inductance L1 connected in series with the primary or secondary circuit forms a main resonant circuit. A demagnetizing device for demagnetizing the core of the transformer after the turn-on phase of the electronic switch is connected to the secondary winding Vl/
at least one additional capacitor c3 connected to 2
The capacitance value fi of this additional capacitor C3 is
, C3 and the shunt inductance of the transformer, L
The inductance connected to the primary and/or output circuit is selected such that the additional resonant circuit with Ll and 01 has a resonant frequency substantially equal to the main resonant frequency of the resonant circuit comprising Ll and 01. additionally provided to
A 94 unit connected directly to the transformer may also be used.

Preferably it is formed by the leakage inductance of the transformer.

Due to the use of a demagnetizing network, virtually no inductive voltage peaks occur in the electronic switch during disconnection. Another advantage is that the core material is optimized for 1 iri use since the transformer is subjected to substantially symmetrical sinusoidal excitation.

In another configuration of the invention, an additional capacitor C3 can be connected with a series resistor Rl' to obtain a better Q-improved result. According to the feature of claim 2, the accompanying high frequency noise is particularly small. Said resistor R1 forms a damping resistance for the additional resonant circuit formed by the inductance L1 and the capacitor 01.

In yet another configuration of the invention, the control input of the electronic switch is connected to the output of a monoflop controlled by a clock with a variable frequency, the output pulses of the monoflop being approximately half as large as the main resonant circuit. The cycle duration time is selected to be the same as the cycle duration time.

In another configuration of the invention, a monoflop was connected to the reference voltage and the output of the conduction converter. l"lj is controlled by a voltage frequency converter with the frequency controlled by a control amplifier.

The starting point according to the configuration of the present invention according to claim 3 is as follows:
When the electronic switch is turned on, the inductance of the main resonant circuit is connected to the capacitor of the demagnetizing device before tR,
It is to limit the charging Km flow.

In the structure of claim 5, another basically (methodically) conditioned high frequency resonance (oscillation) circuit is aperiodically damped (
dump) and does not harm other functions.

The measures according to claim 8 ensure that during the blocking phase, the excitation process is terminated in a targeted manner after a transition (switching) of the excitation current to its maximum negative value is reached. The negative maximum excitation current flows through the diode DI and the diode D2 through which the quantified choke current fL2 flows, and the value does not substantially change until the next on-phase. This is a prerequisite for a certain symmetrical excitation of the transformer.

Other objects, features and advantages of the present invention will become apparent from the following description of specific preferred embodiments, taken in conjunction with the accompanying drawings, but without departing from the spirit and scope of the novel concept of the invention. It should also be noted that there are also possible variations and modifications.

Embodiment The single-ended conduction type converter shown in FIG.
In the primary circuit, the primary winding W1 of the transformer Tr is connected to the DC source Q through an inductance L1 and an electronic switch S.The secondary winding of the transformer Tr The line is in the secondary circuit and rectifier D1
is connected to storage capacitor C1 through.

Primary circuit inductance L1 and storage capacitor C
1 forms a main resonant circuit. Freewheeling diode D2 is connected in parallel to storage capacitor C1. Next to this freewheeling diode 020 is a filter part consisting of a series inductor L2 and a parallel capacitor 02.

Load resistor RL is connected in parallel to capacitor C2, which is the output of the conduction type converter.

A series circuit formed by capacitor 03 and resistor R1 is in parallel with secondary winding 1VV2 of transformer Tr and forms a demagnetizing device. This series circuit is directly and continuously connected to the winding mW2 of the transformer Tr. The capacitance f of the capacitor 03 is selected so that another resonant circuit formed by the capacitance of the capacitor C3 and the shunt inductance of the transformer Tr has a resonant frequency similar to that of the main resonant circuit.

If the inductance of the main resonant coil is completely or partially in the secondary circuit, this RC series circuit is connected to the secondary winding W2 through the inductance.

The electronic switch S is formed by a field effect transistor with a control electrode driven by the driver 1. Driver 1 receives a monoflop of 20 fields. The duration of the output pulse of the monoflop 2 is determined by the RC element convex connected thereto, and is selected to be half the duration of the main resonant circuit.

The gain control amplifier 6 has an inverting input connected to the output of the conduction converter and a non-inverting input connected to the reference voltage Uref. The output of the 1-1 gain control amplifier 6 passes through a photocoupler 5 and reaches a voltage-frequency oscillator 4, which is a monoflop 2 whose repetition rate depends on the output voltage of the photocoupler 5. Output control/9
supply russ.

The output voltage is fed to a gain control amplifier 6 which compares it to a reference voltage Uref. Its output is photocoupler 5
, the voltage-frequency converter is controlled to suppress voltage fluctuations. Its operation is such that an upward variation in the output voltage reduces the frequency of the excavator, and a downward variation increases the frequency of the converter.

The voltage-frequency converter 4 triggers the monoflop 2 every output clock. The duration of the output pulse of the mono 70 tube 2 is selected to be the duration of a half current wave in the switching transistor. This time is Ll
The resonant frequency is determined by the resonant frequency consisting of and 01. In contrast, the respective influence of the input voltage on the load or on the duration and on the duration of the current half-wave of the electronic switch 5 is relatively small. As a result, the on-time of the switching transistor 6 remains constant over the entire range of one operation.

The driver 1 drives the switching transistor 5 based on the output of the monoflop 2.

The functions of the conduction type converter of FIG. 1 are as follows. For simplicity, in this explanation the metamorphic ratio of the transformer Tr is u=
Assume that 1. However, other metamorphic ratios can also be used.

In the first-order approximation formula, the resistor R1 is ignored and considered to be short-circuited. The shunt inductance Lq or the main inductance, respectively, is a larger factor than the leakage inductance or inductance L1, respectively.

The capacitance of capacitor 03 is shunt inductance L
q is selected to form a resonant circuit with q, and the resonant frequency of this resonant circuit is determined as follows.

This value is equal to the resonant frequency of the first resonant circuit formed by the inductance L1 and the capacitor C1, and the resonant frequency of the first resonant circuit is as follows.

After the current in the rectifier Dl becomes zero, the excitation 1'[r
lj 1m remains in the shunt inductance Lq. This shows the power supply UE and the still closed switch S
Initially, it continues to flow through Ndenzer C3. The negative, sinusoidal voltage thus created has a voltage-time curve similar to the positive voltage-time (plane) curve in which the transformer Tr is charged during the on-time. A predetermined operation of the transformer Tr with substantially symmetrical excitation is thus obtained. When the excitation current 1m returns to its maximum value in the negative direction, it becomes Vi 1 and D2
continues to flow through. Due to the very high applied output sound, current in this phase, D2 conducts.

A new cycle begins when the switch flips closed.

When turning on the power again (when P3 turns on), the inductance L
1, together with resistor 1, prevents rapid discharge of capacitor C3 through switch S. The next switching cycle begins immediately upon termination of the demagnetization effect. If f1=12, the following equation holds.

fTAKTmax='l='2 (3) That is, the highest clock frequency corresponds to the common frequency sand.

Since all switching actions are initiated gradually (")7t1), radio frequency interference is minimized, as can be seen in FIGS. 2-4.

The pulse diagrams of FIGS. 2 to 4 show all important current and voltage curves for the conductive transducer shown in FIG. 1 for a full cycle.

FIG. 2 shows the current curve 11 of the primary circuit and the capacitor's pressure Uc1 of the secondary circuit. 6 hours
From EIN to time tAUS, ie during the on-phase, switch S is closed. time t
Time tEIN from AUS.

That is, during the inhibit phase, switch S is open. A switching cycle consisting of a turn-on phase and an inhibit phase is followed by another switching cycle.

1 during the turn-on phase, as shown in FIG.
The electric currents fir, , ll applied to the next-side circuit ff11 are in the form of half-wave sine waves. The inhibition phase that follows, during which no current flows through the primary side, is longer than the turn-on phase and lasts longer.

The voltage UCI appearing on capacitor 01 rises during the turn-on phase. At the beginning of the inhibit phase, and in the first half thereof in the illustrated example, the freewheeling diode D2 is connected to the voltage UCI.
It decreases to the value of 0 on-state it pressure u□. This voltage is maintained until the end of the inhibit phase.

FIG. 3 shows the excitation-like extension. tEIN-tA
At time Us, the voltage UTr appearing in the primary winding W1 of the transformer Tr, assuming a transformation ratio u-1, is equivalent to the capacitor voltage UCI shown in Figure 2, except for the remaining voltage of the diode D1. ·be. In this time period, the shunt inductance Lq of the transformer Tr
i! , excitation electric IAt, l m, i.e. input 1! The difference between the current and the output current increases with the applied voltage.

During the period tAUs-tM, the excitation current 1m oscillates from the maximum positive value to the maximum negative value, basically in accordance with a cosine function. As a result, the voltage UTr in the transformer Tr progresses sinusoidally in the negative direction. When the current passes through the zero axis, the voltage uTr reaches its negative maximum. Since the transformer voltage UTr from the time tAUs is lower than the voltage UCI, the excitation circuit and the output circuit are decoupled by the diode DI (c).

Resonant circuit Lq only at time tM.

C3 tries to increase the transformer voltage UTr in the positive direction again. However, this is prevented by the conducting freewheeling diode D2, which, as already explained, substantially shorts out the excitation 73 current, fm.

As seen at time tM-tEIN, the negative excitation constant current: m remains constant.

Figure 4 is! lF! , *Similar to the 1-voltage ULI, it shows a voltage curve at the switch SK, which is formed by the input voltage UE and the transformer voltage UTr. As shown in FIG. 4, the voltage at switch S is practically zero during the turn-on phase. At the beginning of the inhibition phase, this voltage increases to a maximum value and then decreases to the value of the supply voltage UE. The voltage at switch S remains constant until the end of the inhibit phase.

However, the inductance L1 and the capacitance of capacitor 03 constitute another, undesirable resonant circuit. Since L l > L q, the dough has a central oscillation frequency that is substantially higher than fl and f2, and the frequency is determined by . A resistor R1 is connected in series with the capacitor 03 in order to damp this resonant circuit and eliminate the nine higher frequencies at which the oscillation of frequency f3 overlaps. In order to make the limit non-periodic, it is reasonable to set it as follows.

On the other hand, if the following relationship holds true, the resistor R1 will not substantially affect the demagnetization resonance aperture trace.

L q > L 1 Although the invention has been described in terms of preferred embodiments, it is not intended to limit the scope of modification and modification within the scope of the claims.

ADVANTAGEOUS EFFECTS OF THE INVENTION The present invention provides a single-ended conductive transducer that is relatively inexpensive and does not waste demagnetization energy.

[Brief explanation of the drawing]

Fig. 1 is an electrical schematic diagram of a single-ended conduction type converter according to the present invention, and Fig. 2 shows a capacitor 0.
FIG. 5 is a diagram showing the voltage of the transformer and the current of the primary side circuit, and FIG. 5 is a diagram showing the input voltage of the transformer and the excitation t&, and FIG.
The figure shows the voltage of an electronic switch as a function of time. 1... Driver 2... Monofrotutsu, 3...
RC element, I... Voltage-frequency converter, 5... Switching transistor 6... Gain control amplifier, A
...Output, C""...Capacitor D""...
Diode, LrJ... dielectric, Q... power supply, Rr
J...resistance, S...electronic switch, Tr...transformer, U""...voltage, Wr J...winding. IGI father-in-law---D

Claims (1)

[Claims] 1. A transformer (Tr) and a demagnetizing device, the transformer (Tr) having an electronic circuit that can be turned on and off alternately by control pulses in its primary circuit. The primary winding (W1) is connected to the DC power supply (Q) via a switch (S), and the transformer (Tr) is connected to the storage capacitor (C1) via a rectifier (D1).
a secondary winding (W2), and the storage capacitor (C1
) is an inductor (
L1) forms a main resonant circuit, said demagnetizing device is connected to the transformer (L1) after the turn-on phase of the electronic switch (S).
The demagnetizing device (C3; R1) is provided to demagnetize the core of the transformer (Tr).
), and the capacitance of said further capacitor (C3) is equal to the capacitance of said further capacitor (C3) and the transformer. a shunt inductance of (Tr) and another resonant circuit formed by the main resonant circuit (L1, C1) is selected to have approximately the same resonant frequency as the main resonant circuit (L1, C1). Continuity type converter. 2. Claim wherein each of the one or more further capacitors (C3) is connected to a series resistor (R1), and the demagnetizing device comprises at least one RC series circuit (R1, C3). The continuity converter according to item 1. 3. The inductance of the main resonant circuit is formed by at least one leakage inductance, and the demagnetizing device consists of only one RC series circuit (R1, C3). A conduction type converter according to claim 2, comprising C3). 4. The circuit constant of the resistor (R1) of the RC series circuit (R1, C3) is formed by the inductance (L1) of the main resonant circuit (L1, C1) and the capacitance of the RC series circuit (R1, C3). 4. A conductive transducer according to claim 3, which is selected as a damping resistor for a further resonant circuit. 5. The circuit constant of the resistor (R1) of the RC series circuit (R1, C3) is the inductance (
Conductive converter according to claim 4, in which the resonant circuit formed by L1) and the capacitance of the RC series circuit (R1, C3) is selected to be damped aperiodically. . 6. The control input side of the electronic switch (S) is a monoflop (controlled by a clock with a variable clock frequency).
2) and, for example, a driver (1).
), and the duration of the output pulse of the monoflop (2) is at least equal to the main resonant circuit (L1, C1
), wherein the monoflop (2) is a voltage-frequency converter. (4
) and the frequency of this converter is controlled by the reference voltage (Ur
7. A conduction converter according to claim 6, wherein the conduction converter is controlled by a gain control amplifier (6) connected to the conduction converter (ef) and also connected to the output of the conduction converter. 8. Storage capacitor (C1) and converter output side (A)
A freewheeling diode (D
2) A conduction type converter according to any one of claims 1 to 7, wherein the conduction type converter is provided with an LC filter circuit (L2, C2) having the following.